Fast dispensing fire extinguisher

ABSTRACT

There is disclosed a fire extinguisher which is not pressurized and is madef thin walled light weight molded plastic or a metal container or a mixture thereof. The container is full of fire extinguishing agent. An explosive device, preferably a detonating cord is in the container which when activated causes gas and shock pressure to burst the container instantaneously expelling the fire extinguishing agent onto the fire being treated.

GOVERNMENT RIGHTS

The invention described herein may be manufactured, used and licensed byor for the Government for Governmental purposes without the payment tous of any royalties thereon.

BACKGROUND OF THE INVENTION

Presently used fire extinguishers which dispense solid or liquid fireextinguishing agents are containers made of pressure resistant metalbecause the fire extinguishing agent is stored under pressure in them.The ordinarily used containers are steel. This makes the containersheavy and difficult to handle. In order to provide a means to dispenseall the fire extinguishing agent from the container, a "head space" of25% of the volume of the container is needed. This increases the amountof space needed to store the fire extinguishers and is significant wherelarge fire extinguishers or many fire extinguishers are used to protectan area.

The fire extinguishing agent is dispensed from the fire extinguishersthrough a valve. The valves of conventional fire extinguishers areopened either manually, electrically, thermally or with a squib. Theelectrical or squib actuated valves operate rapidly, but, the volumedispensed is a function of the size of the valve orifice, which in mostcases is of insufficient size to permit substantially instantaneousdispensing of the fire extinguishing agent. Thus, the known fireextinguishers are not suitable for extinguishing fast moving fires likeammunition fires or vehicular fires. These types of fires require largeamounts of extinguishing agent in a very short time since, as is knownin the fire extinguishing art, the faster that a given amount of fireextinguishing agent is applied to a fire, the greater is the probabilitythat the fire will be extinguished. Because of the time needed todispense the fire extinguishing agent, more agent is needed toextinguish a fire than if all the agent in a fire extinguisher isdispensed simultaneously. In mining, grain elevators, oil well drillingoperations and other dangerous situations, large instantaneousapplications of fire extinguishing agents are required to achievemaximum effect.

There is thus a need for a fire extinguisher which will enable all itscontents of fire extinguishing agent to be instantaneously applied to afire and which can be more easily stored safely with smaller spacerequirements than conventional fire extinguishers.

BRIEF SUMMARY OF THE INVENTION

This invention provides non-pressurized rapidly dispensing lightweightfire extinguishers comprising a shaped hollow container with an orificefor receiving a fire extinguishing agent and an explosive device, e.g. adetonating cord, wherein the container is an easily burstablelightweight plastic or thin walled metal. There is a means, e.g. adetonator activated by electricity, heat and the like, for detonatingthe explosive device, e.g. detonating cord, which creates gas or shockwaves or both, causing the container to burst and instantaneouslydispense all the fire extinguishing agent in the container. Thedetonator is an electrically initiated detonator which is outside thecontainer and is operatively connected at one end to the explosivedevice, e.g. to one end of the detonating cord, and at the other end toelectrical leads which can be attached to a source of electricity.

The container walls can be scored to provide weakened areas for ease ofbursting and for controlling the direction the fire extinguishing agentis dispensed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a fire extinguisher of this invention inwhich the container therein is shaped rectangularly;

FIG. 2 is a sectional view taken along line 2--2 of FIG. 1;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 1;

FIG. 4 is a perspective view of a fire extinguisher of this invention inwhich the container therein is a square bottle shape;

FIG. 5 is a sectional view taken along line 5--5 of FIG. 4;

FIG. 6 is a sectional view taken along line 6--6 of FIG. 4.

DETAILED DESCRIPTION OF THE INVENTION

The container of the fire extinguisher of this invention is made of alightweight plastic or thin metal sheet, each of which are inert to anyfire extinguishing agent which might be stored therein. The size andshape of the container is dictated by the type of fires it is intendedto extinguish and the space available to store them. Because thecontainer is completely full, more extinguishing agent for a givenamount of space can be utilized. The shape of the container can bemolded to fit any required space, including those where conventionalextinguishers cannot be accommodated. Thus, for example, the ceiling ofa storage shed or trailer can have a fire extinguisher of this inventioncover a large surface thereof, whereas conventional fire extinguisherswould have to hang on the walls. Since the fire extinguishers of thisinvention do not need to be hand operated, they can be placed in out ofreach places which are more strategic than hand operated devices can bepositioned. The plastics which are suitable for use in making thecontainers used in the fire extinguishers of this invention are thosewhich are easily molded and which are inert to the fire extinguishingagents used, typical of such plastics are polyethylene, polypropylene,polytetrafluoroethylene, acrylics, polycarbonates, polyvinyl chloridesand rubbers. Metals which are suitable for making the containers arethose which can be formed into lightweight sheets that are weak enoughto be burst upon the activation of the explosive device, e.g. detonatingcord, (hereinafter "detonating cord" will be used for convenience in thedescription of the invention although other explosive devices arecontemplated) and which are inert to the fire extinguishing agents used.Typical suitable metals are aluminum and its alloys, and thin steelsheets. The container can also be made from both metal and plastic.

The walls of the containers need be strong enough to contain thecontents but weak enough to break or shatter when the extinguisher isactivated. It is convenient to score the walls of the container so theywill break easier and in predetermined places so the extinguishing agentis dispensed in the desired direction rather than in all directions atonce.

The extinguishing agent can be liquid, solid or mixtures, e.g. powder orgranular, aqueous solutions or aqueous mixtures with powders or granulestherein. The fire extinguishing agent is loaded into the container byconventional means through an orifice in the container. The same orificeis used to load the detonating cord into the container, usually afterthe extinguishing agent is loaded. The cord is relatively rigid andreaches to the wall of the container opposite the loading orifice, e.g.the bottom, if the container is bottle shaped. The cord may be coatedwith a material inert to the extinguishing agent. However, a preferredmethod of protecting the cord is to insert into the orifice of thecontainer a protecting tube made of material inert to the extinguishingagent.

The protecting tube reaches to the wall, or bottom in case of a bottleshape, opposite the orifice and is inserted prior to or with thedetonating cord. The detonating cord can extend through a hole in thewall opposite the loading orifice, but need not. The tube must be weakenough to rupture when the detonator cord is detonated. Once thecontainer is loaded with the extinguishing agent, protective tube (ifused) and detonating cord, a detonator can be attached to the detonatingcord, then the edges of the orifice and rear hole (if present) aresealed.

A detonator is used if the detonating cord is not sensitive enough todetonate when heated by a fire or other means not requiring a detonator.The preferred types of detonators are conventional electricallyactivated or squib activated. The power source can be an electricalsource from, for example, a fire detector or smoke detector.

The choice of fire extinguishing agents depends on the type of fire tobe extinguished, e.g. petroleum fuel, propellants, pyrotechnic mixtures,paper and the like, including those mentioned above. Also the nature ofthe surroundings is a factor, thus, one would avoid salt or aqueousextinguishing agents in the vicinity of electrical systems.

The following are typical suitable fire extinguishing agents: water;water and ethylene glycol; water and foaming agents; water, ethyleneglycol and foaming agents; water and inorganic salts such as alkalimetal chlorides, e.g. sodium chloride, lithium chloride; water, foamingagents and alkali metal chlorides; water and propylene glycol; water,propylene glycol and foaming agents; phosphate salts, e.g. monoammoniumphosphate, diammonium phosphate, potassium phosphate; and high boilinghaloalkanes such as bromochloro methane (Halon 1011).

The invention can be better understood with reference to the drawings.

FIGS. 1, 2 and 3 depict a rectangular parallelepiped container A withthin plastic and/or metal walls 1. The shape is one possible shape asexplained above. An orifice 6 is at one wall of the container A. Thefire extinguishing agent is loaded into the container A through aloading orifice 6. Then a protective tube 2 is inserted into thecontainer A through the loading orifice 6. The tube 2 extends the lengthof the container A. Then a detonating cord 3 is inserted through theloading orifice 6 and can reach the entire length of the container A orextend beyond the rear wall 8 through a hole 9 therein. Attached to thedetonating cord 3 on the end thereof extending from the loading orifice6 is a detonator 4 with electric leads 5. The detonator 4 as explainedabove is a preferred embodiment but is not essential to the invention.The loading orifice 6 is sealed with a sealing gasket 7.

FIGS. 4, 5 and 6 depict a bottle shaped fire extinguisher B. Thenumerals refer to the identical parts defined for those numerals inFIGS. 1, 2 and 3. In the bottle embodiment, the protective tube 2 andthe detonating cord 3 both rest on the bottom inside surface 8 of thebottle.

The fire extinguisher of this invention operates as described for thefollowing typical embodiments:

When an electrical signal is imposed on the electrical leads 5, thedetonator 4 functions, causing the explosive material contained in thedetonating cord 3 to explode. Gases generated by the explosion split theprotective tube 2, instantaneously pressurizing the fire extinguishingagent in the container A or B causing the walls 1 and 8 to ruptureallowing all the fire extinguishing material to be expelledinstantaneously.

When operated on a fire started in the propellant section of a tank gunround, the device of this invention extinguished the fire in 10milliseconds using as the fire extinguishing agent six liters of waterand 2 liters of foaming agent. Nine grams of explosive were used todetonate the fire extinguisher.

In another test, 23 kilograms of burning, compartmentalized M30propellant was extinguished in 60 milliseconds using 36 liters ofextinguishing agent consisting of 30 liters of water and 6 liters offoaming agent. Eighteen grams of explosive were used in the fireextinguisher in which the container was made of metal and plastic.

We claim:
 1. A non-pressurized, lightweight, rapidly dispensing fireextinguisher consisting essentially of:a hollow shaped container havingan orifice, a fire extinguishing agent in said container, an explosivedevice operatively fitted in said container through said orifice, saidcontainer made of a burstable lightweight thin wall metal or plastic,and means for detonating said explosive device to burst said containerand instantaneously disperse all fire extinguishing agent in saidcontainer.
 2. The fire extinguisher of claim 1 wherein the explosivedevice is a detonating cord.
 3. The fire extinguisher of claim 2 whereinthe means for detonating said detonating cord is an electricallyinitiated detonator.
 4. The fire extinguisher of claim 2 wherein thedetonator cord contains a gas-producing explosive.
 5. The fireextinguisher of claim 2 wherein the detonating cord is protected by acovering which is inert to any fire extinguishing agent in saidcontainer.
 6. The fire extinguisher of claim 5 wherein the protectivecovering for the detonating cord is a pipe adapted to burst upondetonation of said cord.
 7. The fire extinguisher of claim 1 containinga sufficient amount of a fire extinguishing agent to extinguishpropellant fires.
 8. The fire extinguisher of claim 1 containingsufficient amount of a fire extinguishing agent to extinguish apetroleum fire.
 9. The fire extinguisher of claim 1 wherein saidcontainer is substantially completely full of fire extinguishing agent.10. The fire extinguisher of claim 9 wherein the fire extinguishingagent is selected from water; water mixed with either ethylene glycol,foaming agents, lithium chloride, sodium chloride, or mixtures thereof;monoammonium phosphate; diammonium phosphate; potassium phosphate orhigh boiling point halogenated hydrocarbons.